A hybrid vehicle having an engine and a motor as a driving source has been known. Such a hybrid vehicle is provided with a power storage device, such as a battery, to store electric power to be supplied to the motor. The battery is charged with electric power generated by a power generator driven by the engine, electric power regenerated using the motor during deceleration of the vehicle, and the like.
Such a hybrid vehicle can travel by using, as the driving source, one or both of the engine and the motor in accordance with a traveling condition of the vehicle or the like. Hence, for example, when the accelerator position is small, the vehicle can travel using only the motor as the driving source with the engine being stopped. Meanwhile, when abrupt acceleration is required, the engine is driven in order to achieve desired acceleration.
In the traveling state in which only the motor is used as the driving source with the engine being stopped, no exhaust gas is emitted, thus achieving small load on environment. However, as described above, in the hybrid vehicle, the stop and start of the engine may be repeated. As a result, the engine may be stopped before completing warming-up of the engine. Accordingly, the engine may be frequently restarted when the warming-up is not completed. As known well, if the engine is started when the warming-up is not completed, a relatively large amount of HC or CO may be emitted.
In order to solve such a problem, each of Japanese Patent Laying-Open No. 2002-256919 (PTL 1), Japanese Patent Laying-Open No. 2002-188481 (PTL 2), and Japanese Patent Laying-Open No. 2010-7532 (PTL 3) discloses to scavenge an exhaust passage or the like by motoring the engine using an electric motor or a starter motor with the engine being stopped.